Watch cases have often been proposed overlaid by a cap.
Patent No. CH-A-558 040 describes a watch case including a protective cap of extra hard material. In this construction the cap is maintained in place by screws perpendicular to the plane of the case traversing the caseband-bezel and being taken up in threaded studs carried under the cap. Here the cap exhibits a rather complicated cross-section in view of these threaded studs. The caseband-bezel must be in a special form in order to be adapted to the cap which overlays it.
Patent No. CH-A-517 963 (U.S. Pat. No. 3,242,664) describes a watch case overlaid by a cap of metallic carbide made of an annular portion surrounding the crystal and two diametrally opposed ears covering the attachment lugs of a bracelet. The annular portion and the ears are respectively brazed onto the case and the lugs. This construction requires special tooling in order to secure the cap onto the watch case and it will be noted that once the cap has been attached, it may no longer be removed, at least not with the employment of simple tools.
The case described in U.S. Pat. No. 4,396,298 contains an electronic module for displaying time. This case includes a back, an elastic portion interposed between the back and the module and a cover. Elastic pins engaged in flanges of the back maintain the module in the back of the case. The same pins serve to attach the cover to the back. The bracelet is fastened to the case by means of ears raised in the back. This construction is complicated and requires several formed and drawn parts. The cover does not properly speaking constitute a cap but rather a basic portion of the case.
Patent Nos. CH-B-352 965, CH-B-358 039 and DE-A-2 753 (equivalent to U.S. Pat. No. 4,186,552) all describe a thin metallic cap overlaying a caseband formed of plastic material. However in each of these documents the caseband is moulded in a single operation to the interior of the cap which renders the cap inseparable once this operation has been effected. In contrast to this and for reasons which will appear hereinafter, the cap of this invention is positioned on a caseband manufactured separately, then hooked to the caseband.
Patent No. CH-B-352 966 shows a cap, not of metal as in the present invention, but of plastic material, the interior surface of this cap being covered with metallization of small thickness. Besides constituting a difficult construction, it will be noted that the outer portions of the cap made of soft material are subject to rapid deterioration (scratches, etc.).